1. Field of the Invention
An embodiment of the present invention relates to an image processing apparatus, an image processing circuit, and a method of controlling the image processing apparatus. Especially, the embodiment of the present invention relates to clock supply control during an energy saving mode.
2. Description of the Related Art
Recently, digitization of information has been promoted and thus image processing apparatuses are inevitable. The image processing apparatuses include, for example, a printer that is used for outputting digitized information and a scanner that is used for performing facsimile communication and for digitizing documents. In many cases, such an image processing apparatus is formed as a multifunction peripheral that can be used as a printer, a facsimile machine, a scanner, and a copier. Namely, the image processing apparatus includes an imaging function, an image forming function, and a communication function.
In such an image processing apparatus, an application specific integrated circuit (ASIC) processes read data input from the scanner and processes image data to be input to a plotter that performs image formation and outputs the formed image. The ASIC performs the above described processing by operating in accordance with clocks supplied from a clock generating unit.
Further, there is an image processing apparatus in which an operating mode may be switched to an energy saving mode where the power consumption is reduced. The operating mode is switched to the energy saving mode by shutting off the power supply to a portion of the apparatus. In such an energy saving mode, the clock generating unit turns off the clock supply, thereby improving the energy saving effect (e.g., cf. Patent Document 1 (Japanese Patent Laid-Open Application No. 2009-145738)).
In the image processing apparatus that is formed as the multifunction peripheral, an image processing unit (IPU) board may be employed. The IPU board is an ASIC that has a function to process the read data from the scanner and a function to process the image data to be input to the plotter.
As for this IPU board, clock supply to the IPU board is preferably turned off during the energy saving mode, so as to improve the energy saving effect. However, power-saving control according to conventional clock control is for a state where an image processing apparatus is not operating, such as the energy saving mode or a standby mode.
In the image processing apparatus including the IPU board, for example, during scanning operation, a function to process read data input from the scanner is operating while a function to process image data to be input to the plotter is not operating. However, the clocks are supplied to all modules included in the IPU board. Therefore, there is a problem such that unnecessary clocks are supplied to some modules, and thereby the power consumption is wasted.